The terms chronograph and chronometer are often confused but actually refer to very different attributes of a watch.

A chronograph is a watch (or other instrument) with two independent time systems, one indicates the time of day and the other measures short time intervals (ie a stop watch function) which allow the exact measurement or duration of an event.

Chronographs can vary greatly in design and function with the stop-start counters relating to seconds, minutes and even hours thus the mini dials on the watch face.

The term chronometer, for Swiss made watches, can only be given to a timepiece that fulfils certain strict criteria and meets a list of very high standards set by the Controle Officiel Suisse des Chronometres (COSC). In addition to this, a chronometer must be capable of permanently displaying the seconds. Clearly, a chronograph watch and a watch that has been certified as a chronometer are two different things. However, a chronograph can also be a chronometer if it has been certified by the COSC.

A Swiss chronometer (with a certificate) is a timepiece of the highest quality. In order to achieve this certification a timepiece must undergo a series of precision tests in the most unfavourable temperature conditions and various positions (vertical, horizontal, side) and found to be within a certain time-keeping accuracy range. For watch movements to be given COSC chronometer status they must not lose more than 4 seconds or gain more than 6 seconds in a day. The COSC make particular note that their testing does not simulate how the watch movement will perform when it is on the wrist as such COSC tests are conducted on a watch movement when it is outside the watch case.

Only about 3% of all Swiss watch production is given COSC certification. This is because many manufacturers either don’t submit their movements to COSC testing (as it is expensive) or do their own testing to superior standards (Germany’s Glashuette standard is higher than COSC). For example Sinn, Lehmann, Moritz-Grossmann, Hentschel, Dornblueth & Sohn, Habring2 and Armin Strom perform their own tests in-house on finished watches (ie watch movement within its case). In these cases the benchmarks are just as high if not higher in some cases.

The Tourbillon, an optional part for mechanical movements, is a rotating frame for the escapement, which is used to cancel out or reduce the effects of gravitational bias to the timekeeping. Due to the complexity of designing a Tourbillon, they are very expensive, and only found in “prestige” watches.

A repeater is a complication in a mechanical watch that chimes the time on demand by activating a pusher or a slide-piece. Different types of repeaters allow the time to be heard to varying degrees of precision, from simple quarter hour repeaters which strike one tone for the number of hours and subsequent tones for each quarter hour, to minute repeaters which strike the time down to the exact minute using a variety of different tones for hours, quarter hours and minutes.

These types of watches have a long heritage in the area of striking watches and are considered one of the most sophisticated and difficult complications to achieve. Originating before the widespread use of electricity, they allowed time to be determined in the dark (and were also used by visually impaired). Now days we can flick on a light to check the watch dial, or it aluminates for us, but the appeal and technical skill required to accomplish a repeater timepiece still fascinates and challenges us.

Ennobling refers to the manual art of enhancing a movement via certain highly skilled techniques as:

• skeletonising (cutting out the non essential parts of a movement to form a design or special motive)
• engraving (etching special designs onto the surface of a movement, eg visible on rotors of automatic mechanical watches)
• guilloching (a traditional technique decorative engraving in which a very precise, intricate, repetitive pattern or design is engraved into a surface)

A crown (also called a stem or a pin) is the button on the outside of the watch case that is used to set the time and date.

In a mechanical watch, the crown also winds the mainspring. In this case it is also called a winding stem. A screwed-in crown (or screwed-down crown) is used to make a watch more water-resistant. The crown actually screws into the case thereby increasing the water-tightness of the overall watch.

Watch dials often feature luminous coating on key functional aspects such as hands, hour markers, numerals etc. This adds functionality and enhances legibility in dimly lit environments but not all lumes offer the same result.
Here is a brief run down.

Basically, there are two main types of lume: photoluminescent (Super-LumiNova, BGW9, C3), which charges in light for a glow that fades over time depending upon the charge, thickness of coating and colour of the lume, and tritium, which uses radioactive gas in tubes for a constant, self-powered glow without charging, though it’s weaker and fades over decades. Modern watches tend to use the safer, non-radioactive which comprises Strontium Aluminate-based compounds like Super-LumiNova. This lume is available in various colours with different brightness levels. White, green and blue lume offer the best visibility while darker colours such as black and grey offer only very muted legibility. It’s always good to think about how you’ll use your watch to get the result that meets your needs.

Modern Lume (Photoluminescent)
These “charge” with light and glow, then fade; they are safe and common. Examples of this type of lume include:
• Super-LumiNova: A brand name for advanced Strontium Aluminate compounds.
• C3: Strongest green glow, often yellowish in daylight, best brightness.
• BGW9: White in daylight, bright blue glow at night, excellent endurance.
• C1: Weakest, white in daylight, faint glow.
• Other Colours: C5 (yellow-green), C7 (green), C9 (blue-green), plus others like orange, red, and purple.
Older & Specialized Lume
• Tritium: Self-powered gas tubes (GTLS) that glow constantly without charging, but weaker and fade over ~12 years.
• Radium: Radioactive, used in vintage watches; dangerous and phased out.
Key Differences
• Charging: LumiNova needs light; Tritium doesn’t.
• Brightness: Green often seems brighter to the eye (human eye’s peak sensitivity), while blue can glow longer (better endurance). Dark colours offer only limited lume and glow time.
• Daytime Appearance: Different pigments look white, yellow, or off-white in the light, while darker colours appear dark.